thecrimsonsatyr
Hi! Design student here - maps in Valorant are crafted in a particular fashion that forces players to hold (and push) common angles. The reason these angles are "common" is since they're usually considered to have practical features: they're out of sight, they hold a wide or tight angle (depending on the gun), they hold a far or close angle (also, dependent on the gun), and you'll probably see your opponent before they see you (if you're a defender). These are just some examples of why common angles are "common", these features aren't limited to what I've said.
So what's my point? Well, you shared that you find yourself being attacked in positions where you've been undetected. Any player who's familiar with common angles will do a number of things to control them, like use utility or randomly pre-fire. Remember, the maps are designed in a fashion that forces players to choose between a limited number of paths and angles, and odds are your enemy will guess those paths and angles right extremely often (especially experienced players).
I'm a Viper main. Let's say I'm in the following 1v2 situation on Bind:
I'm on A point and the bomb has been dropped on-site by the green crates. I'm currently in Heaven with a clear view of the bomb. I have no idea where my enemies are. I believe it's extremely unlikely that I'll be flanked - not because I heard gunfire elsewhere, but because it's a rare experience for players to push the flank on Bind. Knowing this, I send Snake Bites (mollies) on A short and Showers. After my Snake Bite hits Showers, I pre-aim, see an enemy run out from my Snake Bite, and kill him. The enemy might be thinking "How did he know where I was?" or "This guy has walls" - but that's just not it. It's something that takes time. A combination of map understanding, common player habits, and "game sense".
If you continue to find yourself struggling with this issue, I highly encourage you to try other agents. Someone like Sova or Cypher may be perfect for you - he can recon before pushing an angle, allowing you information beforehand. You can also try smoke/flash based agents to mix up your game play and make your pushing less predictable.
Don't forget to have fun!